Lesson steps

1. Piano key note names

This step shows the white and black note names on a piano keyboard so that the note names are familiar for later steps, and to show that the note names start repeating themselves after 12 notes.

The white keys are named using the alphabetic letters A, B, C, D, E, F, and G, which is a pattern that repeats up the piano keyboard.

Every white or black key could have a flat(b) or sharp(#) accidental name, depending on how that note is used. In a later step, if sharp or flat notes are used, the exact accidental names will be chosen.

The audio files below play every note shown on the piano above, so middle C (marked with an orange line at the bottom) is the 2nd note heard.

6. Triad chord note intervals

This step defines the note intervals for each chord quality, including the intervals for the D-sharp diminished triad chord.

Each individual note in a triad chord can be represented in music theory using a note interval, which is used to express the relationship between the first note of the chord (the root note), and the note in question.

The root note is always the 1st note (note interval 1 in the above diagram) of the major scale diagram above. ie. the tonic of the major scale.

Then there is one note interval to describe the 2nd note, and another to describe the 3rd note of the chord.

In the same way that the entire chord itself has a chord quality, the intervals representing the individual notes within that chord each have their own quality.

Below is a table showing the note interval qualities for all triad chords, together with the interval short names / abbrevations in brackets.

Triad chord note interval qualities

Chord quality

2nd note quality

3rd note quality

major

major (M3)

perfect (P5)

minor

minor (m3)

perfect (P5)

augmented

major (M3)

augmented (A5)

diminished

minor (m3)

diminished (d5)

suspended (2nd/4th)

major (M2) or perfect (P4)

perfect (P5)

The numbers in brackets are the note interval numbers (ie the scale note number) shown in the previous step.

D-sharp triad chord note intervals

Looking at the table above, the note intervals for the chord quality we are interested in (diminished triad), in the key of D# are D#-min-3rd and D#-dim-5th.

The links above explain in detail the meaning of these note qualities, the short abbrevations in brackets, and how to calculate the interval note names based on the scale note names from the previous step.

7. D-sharp diminished triad chord in root position

Note name adjustments

Each note interval quality (diminished, minor, major, perfect, augmented) expresses a possible adjustment ie. a possible increase or decrease in the note pitch from the major scale notes in step 4.

If an adjustment in the pitch occurs, the note name given in the major scale in step 4 is modified, so that sharp or flat accidentals will be added or removed.

But crucially, for all interval qualities, the starting point from which accidentals need to be added or removed are the major scale note names in step 4.

For this chord, this is explained in detail in D#-min-3rd and D#-dim-5th, but the relevant adjustments for this diminished chord quality are shown below:

D#-3rd: The 3rd note quality of the major scale is major, and the note interval quality needed is minor, so the 3rd note scale note name - F##, is adjusted 1 half-note / semitone down to F#. The chord note spelling reflects this note flattening: b3.

D#-5th: The 5th note quality of the major scale is perfect, and the note interval quality needed is diminished, so the 5th note scale note name - A#, is adjusted 1 half-note / semitone down to A. The chord note spelling reflects this note flattening: b5.

D-sharp diminished triad chord note names

The final chord note names and note interval links are shown in the table below.

The piano diagram below shows the interval short names, the note positions and the final note names of this triad chord.

In music theory, this triad chord as it stands is said to be in root position because the root of the chord - note D#, is the note with the lowest pitch of all the triad notes.

The note order of this triad can also be changed, so that the root is no longer the lowest note, in which case the triad is no longer in root position, and will be called an inverted triad chord instead.

For triad chords, there are 2 possible inverted variations as described in the steps below.

Figured bass notation

The figured bass notation for a triad in root position is 5/3, with the 5 placed above the 3 on a staff diagram.

These numbers represent the interval between the lowest note of the chord and the note in question.

So another name for this chord would be D-sharp diminished triad in five-three position.

For example, the 5 represents note A, from the D#-5th interval, since the triad root, D#, is the lowest note of the chord (as it is not inverted).

In the same way, the figured bass 3 symbol represents note A, from the D#-3rd interval.

Since figured bass notation works within the context of a key, we don't need to indicate in the figured bass symbols whether eg. the 3rd is a major, minor etc. The key is assumed from the key signature.

Often, for a triad in root position, these symbols usually not shown at all, since it is assumed that the triad is shown in root position (ie not inverted), unless otherwise indicated as shown below.